摘要:

SUMMARYThe behaviour of the Sociable WeaverPhiletairus sociuswas studied briefly in South Africa in 1969, and more extensively in aviaries in southern California for over three years (1972‐75). The species was bred successfully in captivity, apparently for the first time.Building of the compound nest in nature is reviewed in the light of preceding accounts, both by ourselves and by others. The optimal preference for nest materials was experimentally determined. Male and female appear identical and there seems to have been no previous detailed account of the behaviour of Sociable Weavers based on distinctively colour‐ringed individuals of known sex. Among the sex differences in behaviour are the amount and nature of building, dominance, malespecific song, and sex differences in relative share of incubation and in the care of nestlings and fledglings. In addition, we describe in detail for the first time certain rarely observed behavioural acts including precopulatory courtship and copulation. Allopreening and water bathing are very rare in this species, and the birds do not take dust ba

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb04994.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYNestling birds may differ in size and weight on the first day a clutch is fully hatched, mainly because eggs within clutches hatch over a period of several days. This asynchronous pattern of hatching is usually thought to facilitate brood reduction when the food supply is unpredictably restricted. The purpose of the study reported here was to examine the contribution of egg‐weight, clutch‐size, hatching spread, food supply and season to weight differences in newly hatched broods of the House Martin.At laying, heavy eggs had a greater moisture and dry weight content than light eggs and immediately before hatching there was a correlation between initial egg‐weight and the dry weight of embryo and yolk. Heavier clutches also tended to give rise to heavier hatchlings. There was, however, no correlation of fresh egg‐weight with the dry weight of embryos alone and the relative dry weight of embryos in a clutch was dependent on laying sequence.Hatching spread (the number of days between the emergence from the egg of the first and the last hatchling of the clutch) was 0.75 ± 0.46 days for clutches of two and increased with the size of the clutch up to 1.80 ± 0.79 days for clutches of five. When food was scarce during laying, hatching spread was greater. Weight difference in newly hatched broods was correlated with hatching spread and moreover in multivariate analysis was also correlated with periods of food scarcity during laying.It was concluded that all examples of weight hierarchies among hatchlings should not be considered adaptive; in some cases they may be imposed by food scarcity. This can lead to mortality of the runs even if food is plentiful. When the weight hierarchy is not adversely accentuated by food scarcity it may function as previously suggested, to allow brood reduction. Alternatively, particularly among House Martins, it may spread out the peak food needs of individual nestlings thereby spreading the demand on t

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb04995.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYA comparative study was made of social organization during breeding among the genusMalimbus. InM. nitens, the male chooses the nest site, builds the nest alone, guards the nest during incubation, and feeds the young; the female incubates, broods alone and with the male feeds the young. InM. malimbicus, the male chooses the nest site, builds the nest with the female and guards the nest; the female builds the nest with the male, but incubates alone. InM. racheliaeandM. cassini, the nest is built by one female and a multi‐male party of two or three. One male drives off the other males when the nest is completed. One male and one female incubate alternately. The female seems to be the leader of the building group, and works like a male. InM. coronatus, the nest is built by a mixed party of males and females (3–6 birds), all working together without any overt leadership. Only one male and one female however, incubate, brood and feed the young.In their morphology and behaviour,Malimbusspp. are close to the weaver birds of the genusPloceus. M. nitensseems the least evolved species whileM. cassiniandM. coronatusare behaviourally the most evolved. In the last species, which has a very elaborate nest, the pair of breeding birds is helped by one to four other birds. These helpers are birds in full adult plumage, and are probably capable of breeding and may do so at another period in the long breeding season of at least six mon

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb04996.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYBreeding and kleptoparasitism of Arctic Skuas was studied at Vik, Iceland, in 1973. Hatching success was 88.9%; fledging success was 0.27 fledglings per pair. The heavy chick mortality occurred mostly in the first week after hatching. In the early part of the breeding season skuas fed by robbing kittiwakes of their food at sea and by eating arthropods at the breeding grounds. At the time of hatching of skua eggs, which coincided with the hatching of Puffin eggs, skuas switched their feeding activities to kleptoparasitism of Puffins and fish so obtained was the principal item of most skuas' diet thereafter. In the first week post‐hatching, the energy balance of an average adult skua pirating Puffins was estimated to be negative, but changed to positive a week later, although later, coinciding with an influx of non‐breeders it turned back to negative. Arctic Terns which normally breed at Vik, and are exploited by skuas, failed to breed in 1973, and the abnormally heavy chick loss is therefore attributed to this failure of the terns.The success of the skuas kleptoparasitizing Puffins depends on the proximity of the interactions to the cliff or to the ocean, where Puffins seck refuge. Skuas catch fish mostly in the air, especially if it is dropped from high. Fish dropped from low is mostly taken by competing gulls and Ravens, which mostly control the ground and lower airspace. Skuas chasing in groups enhance their success, but the average success per member decreased with group increase. However, the success of the group‐member in the ‘best’ position was equal to that of a single skua. Puffins carry 1 (large)‐6 (smaller) fish, an approximately equal load irrespective of number of fish. Skuas preferentially chase Puffins carrying ‘large’ fish, thus maximizing their yield per effort. Arctic Skuas responded to changes in the numbers of arriving Puffins with a functional response, but their monitoring of the food supply was f

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb04997.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb04998.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb04999.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb05000.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb05001.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb05002.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1978.tb05004.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY